Ketogenic diets for drug‐resistant epilepsy
Epilepsy is a disorder where recurrent seizures (fits) are caused by abnormal electrical discharges from the brain. In most people seizures can be controlled by one or more antiepileptic medicines, but seizures may not be helped by these medicines after a while (called drug‐resistant epilepsy). For people who have drug‐resistant epilepsy, a special diet (called a ketogenic diet) may be considered. Ketogenic diets are high in fat and low in carbohydrate.
This review aimed to investigate the effect of ketogenic diets on seizure control, cognition (e.g. learning, concentration and academic performance in children; learning, concentration and memory in adults) and behaviour. We also investigated the side effects of the diet and the number of participants who dropped out of the studies and the reasons for this.
We searched medical databases for randomised controlled trials (clinical studies where people are randomly put into one of two or more treatment groups) of adults or children with epilepsy, where a ketogenic diet was compared with other treatments. We found 11 randomised controlled trials, with 778 participants. The trials were between two and 16 months long.
The short‐term side effects of ketogenic diets included diarrhoea, constipation and vomiting. Long‐term effects are unknown from these studies.
All studies reported participants dropping out, due to lack of improvement in seizures and poor tolerance of the diet.
One study reported upon the effect of ketogenic diets on quality of life, cognition and behaviour. No difference was found in the quality of life of those following a ketogenic diet and the group receiving care as usual, but participants following the ketogenic diet were found to be more active, more productive and less anxious. More research is needed in these areas.
Recently, other, better tolerated, ketogenic diets, such as the modified Atkins diet, found similar effects on seizure control as those more restrictive ketogenic diets. However, more research is required.
Quality of the evidence
The studies included in this review were limited by small numbers of participants and only children were included in 10 of the 11 studies, therefore, we judged the quality of the evidence to be low to very low.
There is little research at present into the use of these diets in adults, therefore, more research is required in this area.
This evidence is current to April 2017.